Log-based Hardware Transactional Memory (HTM) systems offer an elegant solution to handle speculative data that overflow transactional L1 caches. By keeping the pre-transactional values on a software-resident log, speculative values can be safely moved across the memory hierarchy, without requiring expensive searches on L1 misses or commits.
Lupon, M.; Magklis, G.; González, A. "A selective logging mechanism for hardware transactional memory systems". 2011.